Three main factors account for South Florida's generally good air quality: Location, geography and meteorology.

Located on a long peninsula jutting out from the mainland, pollutants have to drift a long way to get to Port St. Lucie, according to Patrick Gillespie, a spokesman for the Florida Department of Environmental Protection.

Since there are no valleys or basins in the area, polluted air doesn't get trapped. And the subtropical breezes that blow much of the time keep things circulating. "Bad air doesn't linger," said Gillespie.

The area has also improved air quality by limiting emissions from local power plants, he said. The plants have mostly now switched over to natural gas, with nitrous oxide levels dropping 80% over the past 10 years.